Patients with metastatic renal cell carcinoma (mRCC) and bone metastasis treated with immunotherapy (IO) with and without prior radiation therapy (XRT) showed no major differences in clinical outcomes, according to research presented at the International Kidney Cancer Symposium (IKCS) 2021.
To evaluate the potential synergistic interaction between XRT and IO in mRCC, the investigators conducted a retrospective review of patients with bone metastasis treated with IO combination therapy, with (defined as within 6 months of IO) and without prior XRT at the Vanderbilt-Ingram Cancer Center in Nashville, Tennessee. Outcomes of interest were progression-free survival (PFS), overall survival (OS), and objective response rate (ORR).
The study included 28 patients, 12 with prior XRT and 16 without prior XRT. Baseline characteristics were similar between the groups, except for prior nephrectomy. The median patient age was 56 years. Most patients had clear cell histology (82%) and intermediate/poor risk (81%) and 25% of patients received prior systemic therapy. Prior nephrectomy was more frequent in the no-XRT group (81%) than in the XRT group (42%).
Patients with prior XRT received ipilimumab/nivolumab (75%), pembrolizumab/axitinib (17%), and avelumab/axitinib (8%). Those without prior XRT received ipilimumab/nivolumab (50%) and pembrolizumab/axitinib (50%).
Between the no-XRT and XRT group, no significant difference was observed for ORR (19% vs 17%; odds ratio, 0.87; 95% confidence interval [CI], 0.12-6.21; P =.89), median PFS (3.5 vs 2.8 months; hazard ratio [HR], 1.05; 95% CI, 0.46-2.3; P =.90), or median OS (18.8 vs not reached; HR, 0.20; 95% CI, 0.03-1.62; P =.13).
Limitations of the study included the single-center, retrospective design and small sample size.
“In our single-center retrospective analysis, no major difference in clinical outcomes were observed in patients by receipt of prior XRT,” the investigators concluded. “Further studies are needed to evaluate the role of XRT prior to immunotherapy.”
Yasin H, Chen YW, Tucker M, Beckermann KE, Rini B. Radiation prior to combination-immunotherapy in patients with metastatic renal cell carcinoma (mRCC) and bone metastases. Presented at IKCS 2021; November 5-6, 2021. Abstract N20.